Local variability in growth and reproduction of Salix arctica in the High Arctic

Abstract

Arctic terrestrial ecosystems are heterogeneous because of the strong influences of microtopography, soil moisture and snow accumulation on vegetation distribution. The interaction between local biotic and abiotic factors and global climate patterns will influence species responses to climate change. Salix arctica (Arctic willow) is a structuring species, ubiquitous and widespread, and as such is one of the most important shrub species in the High Arctic. In this study, we measured S. arctica reproductive effort, early establishment, survival and growth in the Zackenberg valley, north-east Greenland. We sampled four plant communities that varied with respect to snow conditions, soil moisture, nutrient content and plant composition. We found large variability in reproductive effort and success with total catkin density ranging from 0.6 to 66 catkins/m² and seedling density from <1 to 101 seedlings/m². There were also major differences in crown area increment (4–23 cm²/year) and stem radial growth (40–74 µm/year). The snowbed community, which experienced a recent reduction in snow cover, supported young populations with high reproductive effort, establishment and growth. Soil nutrient content and herbivore activity apparently did not strongly constrain plant reproduction and growth, but competition by Cassiope tetragona and low soil moisture may inhibit performance. Our results show that local environmental factors, such as snow accumulation, have a significant impact on tundra plant response to climate change and will affect the understanding of regional vegetation response to climate change.

• Herbivory
• nutrient
• plant colonization
• vegetation
• shrub
• water availability.

To access the supplementary material for this article, please see the supplementary files under Article Tools, online.

To access the supplementary material for this article, please see the supplementary files under Article Tools, online.

Acknowledgements

Special thanks to Christian Bay for his advice and help in the field, Sylvie Ferland, Laurianne Bonin and Charlotte Kure Brandstrup for laboratory assistance, as well as Greg Henry for comments on the manuscript. This work was made possible by the financial support of the Fonds québécois de la recherche sur la nature et les technologies, the Northern Worlds initiative of the National Museum of Denmark, the Natural Sciences and Engineering Research Council of Canada, the Northern Scientific Training Program and ArcticNet—a Network of Centers of Excellence of Canada. The Arctic Research Centre, Aarhus University, provided logistical support for the fieldwork.

Notes

To access the supplementary material for this article, please see the supplementary files under Article Tools, online.